Re: [Buildroot] [PATCH 1/1] package/pkg-cmake.mk: add Platform/Buildroot-Initialize.cmake

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

On Sat, Jan 17, 2026 at 11:31:09AM +0100, Julien Olivain via buildroot wrote:
> Since commit [1] (core/pkg-cmake: provide our own platform
> description), Buildroot is setting its own CMake platform
> description. This description applies minor changes on top of
> the CMake Linux platform, see [2] and [3]. The CMake system specific
> script tries to include an initialization script, if present.
> See [4].
> 
> Since in commit [1] we set the CMAKE_SYSTEM_NAME to "Buildroot"
> (rather than "Linux"), CMake will search for a
> "Platform/Buildroot-Initialize.cmake" which does not exist, and
> continue normally, since the include is optional.
> 
> The "Platform/Linux-Initialize.cmake" file is the one setting the
> LINUX [6] and UNIX [7] variables, which are expected to be true on
> a linux compatible system. In Buildroot, it is currently not
> included, so those variables are unset.
> 
> If a CMake package in Buildroot has a construct such as:
> 
>     if(LINUX)
>         # ...do things...
>     else()
>         message(FATAL_ERROR "System not supported")
>     endif()
> 
> It will fail at configuration time.
> 
> This situation happened when trying to add the btop++ package
> in Buildroot. See [8].
> 
> Since the initial intent of commit [1] was to make the Buildroot
> CMake system inherit from Linux plus some fixups, this commit simply
> adds a Buildroot-Initialize.cmake file that includes the
> Linux-Initialize.cmake one from CMake. This will have the effect
> to properly define the LINUX and UNIX variables.
> 
> [1] https://gitlab.com/buildroot.org/buildroot/-/commit/c69b14fe2f72d8134057b115884c04a2bf27d410
> [2] https://gitlab.com/buildroot.org/buildroot/-/blob/2025.11/support/misc/Buildroot.cmake#L1-4
> [3] https://cmake.org/cmake/help/v4.2/variable/CMAKE_SYSTEM_NAME.html
> [4] https://gitlab.kitware.com/cmake/cmake/-/blob/v4.2.1/Modules/CMakeSystemSpecificInitialize.cmake#L35
> [5] https://gitlab.kitware.com/cmake/cmake/-/blob/v4.2.1/Modules/Platform/Linux-Initialize.cmake
> [6] https://cmake.org/cmake/help/v4.2/variable/LINUX.html
> [7] https://cmake.org/cmake/help/v4.2/variable/UNIX.html
> [8] https://github.com/aristocratos/btop/blob/v1.4.6/CMakeLists.txt#L76
> 
> Reported-by: Gilles Talis <gilles.talis@gmail.com>
> Signed-off-by: Julien Olivain <ju.o@free.fr>

Applied, thanks!

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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